Assembly and realisation of synchronisation rings in the form of sheet metal parts shaped without cutting

ABSTRACT

An arrangement of non-machined sheet metal synchronizer rings ( 1, 6, 10, 18, 19, 21 ) is provided, the outer synchronizer rings ( 1, 6, 10, 19 ) of which are provided a radial, outwardly projecting gear ring and a radial, outwardly directed flange ( 3 ).

BACKGROUND

The invention concerns a synchronizing apparatus for a manual shifttransmission with:

a stationary, synchronizer body possessing torsional strength andcircumferentially encompassing a gear shaft,

a movable sleeve on the synchronizer body, slidable along thelongitudinal axis of the gear shaft,

at least one shift gear (16), rotatably placed on the gear shaft andwhich can be coupled to the synchronizer body (13) by the moveablesleeve (14), which gear is provided with a clutch body (17) or with aclutch gearing, and can be joined to the synchronizer body (13) by theclutch body or the clutch gearing,

at least one friction element connected to the shift gear

and at least one outer synchronizer ring having torsional strengthconnected to the synchronizer body,

wherein the outer synchronizer ring comprises essentially a conicalbody,

with that end piece thereof, of the greater diameter, being proximal tothe shift gear, and that end piece thereof, of the smaller diameter,being proximal to the synchronizer body,

which is provided on its outer surface with a gear ring directedradially outward,

and the inner surface of which is designed as a friction surface whichcoacts with a friction element.

A synchronizing apparatus of this general type is described by EP 0 717212A1. In this synchronizer apparatus, the friction element is formed bya conically designed friction ring with friction surfaces provided onboth its inner and outer surfaces. These friction elements are alsodesignated as an interposed ring and mesh with engaging cams, whichproject from its greater diameter end, matching with counter recesses ofa clutch body. The friction surface on the outer exposed surfaceremains, during the synchronizing process, in a friction-lockedconnection with a corresponding friction surface on the outersynchronizer ring. At the same time, a friction surface, placed on theinner surface of the interposed ring, enters into a like frictionconnection with a friction surface of an inner synchronizer ring. Theouter synchronizer ring is in a form-fit connection with thesynchronizer body and engages with cams—which project radially inwardlyfrom the lesser diameter cone end—matching recesses in the innersynchronizer ring. The inner synchronizer ring is thus, by means of theouter synchronizer ring, again in form-fit connection with thesynchronizer body.

An improved ability for clutches in motor vehicle manual shifttransmissions to carry greater stresses places continually growingdemands on the components of the transmission. Corresponding with thegreater load carrying ability of these clutches, the inertial moments tobe braked in the transmission by the synchronizer rings also increase asthe synchronizing proceeds. The required greater frictional forces to beproduced, are generally brought about by greater frictional areas, thatis, increasing the size of frictional surface pairs.

Also, as a rule, the diameter of the rings, i.e. the active width of thefrictional surfaces, is increased, or, alternately, multiplesynchronizing apparatuses are installed, that is, a plurality ofsequential, interposed synchronizer rings are added. The entiresynchronizing apparatus is thus larger, heavier and requires more spacein the transmission.

Correlated to the demand for greater load capacities of synchronizingapparatuses, is a requirement that these apparatuses be of low weightand occupy a small installation space. Thus, in the design of modemsynchronizing, a contradiction is created, between requirements for ahigher friction capacity of synchronizing units and for theirconstruction, sparing of both weight and installation space. Knownsolutions to this problem, in accord with the present state of thetechnology, are to be found in that the synchronizing rings are placedpartially inside the allotted construction space of both thesynchronizer body and the slide sleeve, and that one or more of theemployed synchronizer rings is made of thin-walled, deep-drawn sheetmetal.

The above references as to the state of the technology describe anarrangement, in which a deep-drawn outer synchronizer ring, athin-walled interposed ring, and relatively massively built synchronizerring are sequentially placed together. Theoretically, the width of thissynchronizer ring arrangement would be designed only to the width of thebreadth required for the friction capacity. From a practical standpoint,space requirements of elements for form-fit connection of the rings,along with their connection construction, such as matched catch andrecess union, have yet to be given serious consideration.

The axial length of a synchronizing apparatus is essentially determinedby the construction and the arrangement of such catches. As far as theoutside width of the above embodiment in accord with the state of thetechnology is concerned, radially inward projecting, engaging catches ofthe inner synchronizer ring work disadvantageously counter to thelength. Since such a synchronizer ring arrangement in a synchronizingapparatus, as a rule, is carried out twice, that is, left and right ofthe transverse middle plane of the synchronizer body, the requiredoccupation of space is not a trivial matter. Sufficient axialinstallation space, as a rule, is available for a connection of frictionrings by means of catches to the gear rings. The recesses necessary forthis can be made in the convenient thick wall structure of the clutchbody or the gear ring.

The outside width of a synchronizer and the weight, with which asynchronizer ring arrangement can be fitted into the synchronizer body,is essentially dependent, on how the shape-fit between the friction ringand the synchronizer body is designed. Of particular difficulty in thismatter is the shaping of non-machined outer synchronizer rings, sincehere, besides the elements for the form-fit, also a key and detentelement for a locking element of the synchronizing apparatus is to beprovided and the rules of drawing mold release have to be observed,where non-machined manufacture is intended.

Particular attention is also to be given to the construction of theouter synchronizer ring. The shape of the generic type of an outersynchronizer ring is described in DE 35 19 811 C2. The axial extent ofthis ring is governed by the necessary thickness of its frictionalsurfaces. The shape-fit to neighboring components is effected by arecessed outer gear ring and by matching detents. The detents are formedfrom lugs, which, by being bent by other projecting tongues to thesurface of the synchronizer body lie symmetrically directed. Projectingoutward from that end of the ring on which the larger diameter of theconical shape is found, the aforesaid lugs point, with their free endsin the direction of the smaller diameter end of the conical ring. Theselugs, during the manufacturing process and after the drawing, arestamped out of the like rim of the bowl-like object together with thegear ring and are subsequently bent. Form fitting connections, extendingfrom the end with the smaller diameter, which match synchronizer ringsof this type, can only be made by lugs, which longitudinally extend overthe entire axial length of the synchronizer ring. The longer a lug is,the much more difficult it will be to exactly align the same in itsproper position and place. The manufacturing demands in labor and time,and hence in fabrication costs, are increased, for instance byadditional calibration. The width of such a detent actsdisadvantageously to the precision of such a detent. The wider, and alsothe thicker the lug is made, just so much more difficult is its exactshaping.

High capacity synchronizing apparatuses encounter high torques, and veryfrequently, abrupt momentum peaks occur. Any lug construction musttransmit such moments and peaks. The cross-sections of said lugs arecorrespondingly subjected to high shear and bending stresses. The lugs,on this account, must be thick in design and be made with high strengthmaterials. Technological limits, as already mentioned, restrict themanufacture of such lugs as to their cross-section in synchronizer ringsof the generic type.

Besides the increased ability for high capacity, the reduced weight, thelessening of the required installation space and the functional safety,the costs for manufacture form a further obstacle which must be takeninto consideration in the design of a synchronizing apparatus. Asubstantial portion of the costs of the manufacture of synchronizerrings arises in that effective friction pairing must be created.Presently, conventional friction pairings are, for instance, steel-brasspairs or synchronizer rings with an extra friction coating such assinter coating or paper coating. In the case of nonmachine manufacturedsynchronizer rings, the friction layers are applied in additionaloperations, before or after the machine-free shaping. The costs are veryhigh for additional material, the costs of additional tooling, andadditional work steps become necessary.

SUMMARY

Thus, the object of the invention is to create a design of synchronizerrings, which avoids the above mentioned disadvantages. Particularattention is directed to the formation of an outer synchronizer ring,which, without detriment to its load capacity, maintains an axialassembly space as small as possible and reduces the costs for themanufacture of synchronizer rings.

This purpose is achieved by the object of claim 1, in that the outersynchronizer ring is: of one piece, thin-walled, essentially conicallyshaped, and fabricated without machining. Further, on the largerdiameter end thereof is located the gear ring and on the smallerdiameter end thereof is a radially outwardly directed flangelike rim.This rim can be shaped from the same material which is employed in theforming of the bottom of a bowl-like shape with conical walls. Thismaterial can be, for example, stamped and turned, or folded to flange.The gear ring and, at times, also the detents are shaped from the upperrim of the conical bowl. The rim found on the smaller conical diameterof the ring and the rim on the greater conical diameter of the ring, arepreferably parallel to one another and in planes transverse to thelongitudinal axis of the synchronizer ring. Since the gear ring and therim are respectively placed on the ends of the synchronizer ring, theseform ideal contact surfaces. The precision of dimensioning of thefabricated end pieces is very high and, by means of a grinding procedurewhich follows the metal forming, can be improved still more. The innersurface of the outer synchronizer ring can be completely converted to afriction surface. The flange to flange distance of the synchronizer ringis thus exclusively governed by the necessary axial extension of thefriction surface. The active size of the contact surfaces is determinedby the diameter of the gear ring plus the radial extension of the gearring and detents on one end and the outside diameter of the flange onthe other end. The same measurements as those of massively designedsynchronizer rings can be achieved. The advantages of a sheet metal ringshaped in this manner lie in its light weight and its low cost offabrication.

A preferred embodiment of the invention provides, that the flange, onits outer circumference, is turned up into a collar. This collar canserve for the reinforcement of the synchronizer ring or be employed as aguide element. The collar is bent out of the material of the flange andextends with its free edge in the direction of the gear ring. A flange,even without such a collar, lends a high degree of shape stability to asynchronizer ring undergoing heat treating. This opens the way forvarious means of heat treating, such as penetration hardening, casehardening, nit riding and further useful processes. Additional costs forreworking, or grinding due to heat distortion of the synchronizer ringare no longer necessary. By the choice of different heat treatmentprocedures, different degrees of abrasion resistance can be achieved.

A flange constructed on the synchronizer ring provides the opportunityfor a multiplicity of shaping possibilities dependent upon the functionof the outer synchronizer ring and on the design of its neighboringcomponents. In this way, in a further advantageous embodiment of theinvention, the flange can be provided with recesses. These recesses canbe brought only partially into the flange, or the flange can undergo afull cutout to the circumference. These recesses serve as guide zonesfor the synchronizing elements such as pressure elements for theshape-fit connection, with, for instance, the synchronizer body. Torquemoments, radially directed, are transmitted through areas of extendedcircumferential lengths, hence, large cross-sections are called for.

Many shaping possibilities exist for contact surfaces, for instance, thecontact of the sliding sleeve during pre-synchronizing. The flangeitself can serve as a contact surface. Also, from the flange, separatedetents can be created by simple metal working. An advantageousembodiment of the invention provides, that detents can be built into thetoothing, which detents extend in the direction of the small conediameter, that is pointed in the direction of the synchronizer body.Each detent lies, viewed from the axial direction, directly over arecess. As the presynchronizing proceeds, pressure elements are guidedinto the recesses and are fixed in this position during thepresynchronizing process. These detents are made, for instance, bystamping or punching. The increment of spatial distance to the elementscoacting in presynchronizing, for instance, to the pressure elements ,can be determined to a very precise degree.

In the case of the outer synchronizer ring in the synchronizingapparatus, where smaller inertial moments and moment peaks are the rule,it is also possible to bring about a form-fit connection by means ofcatch elements, that is, connection to the inner synchronizer ring. Asis described in yet another embodiment, on the smaller diameter of thecone, that is, on the smaller end of the outer synchronizer ring, areprovided radially inwardly projected cams. For these cams,advantageously the material is employed, which was removed for theformation of the recesses in the flange. In this way, during the metalworking, for instance, the necessary cams and therewith the recesses canbe stamped out of the base. The flange is then pressed outward and thecatches are bent inwardly.

The aforesaid object is further achieved, in that an outer synchronizerring is now created which meets the specifications of being ofone-piece, thin-walled and non-machined sheet metal (is, formed withchip removal) and is of the above described formulation, with aninterposed ring and an inner synchronizer ring. The interposed ring andthe inner synchronizer ring are likewise designed as non-machined, pressformed sheet metal components. Due the fact, that the outer synchronizerring requires only a small space because of its radial, outwardlyextending flange, the space requirement is minimal for the entiresynchronizing apparatus, comprising three or more rings. Since all ringsare-thin-walled, in total, they have a relatively small weight. Thecosts for the non-machined synchronizer rings is also relatively small.In this arrangement, the outer synchronizer ring, by means of at leastone recess placed in its flange, is connected by form-fit with thesynchronizer body and thus acquires torsional strength. The innersynchronizer ring is form-fit connected directly with the synchronizerbody. The connection is made in an advantageous manner by an inwardlydirected, radial flange on its smaller circumference, which is providedwith at least one recess: The flange and the recess of this innersynchronizer ring were produced by metal forming of the draw processfrom the bottom of the cone shaped bowl. One may, however, consider thatthe form-fit connection and the prevention of twist of the innersynchronizer ring can be effected by the known, inwardly directedcatches.

The already economically designed and constructed synchronizer ringarrangement can be even more economically produced, if, as is describedin an advantageous embodiment of the invention, the steel surfaces ofthe coacting rings also form the friction surfaces of the rings.Provision also has been made, that no separate friction coating need beadded. The required frictional characteristics are achieved in accordwith the requirements and the application by the combination of thefollowing variants:

The combination of assorted kinds of steel. Example: 100 Cr-6 and deepdraw steel.

The combination of different surface hardenings, example: matching anunhardened friction surface against a case hardened friction surfacewith a friction surface of a penetration hardened ring.

The pairing of friction surfaces of different surface structures.Example: The matching of a surface that is stamped and corrugated with asmooth surface. The pairing of frictional surfaces with different groundsurfaces, wherein the thereby stamped or ground corrugations cansimultaneously be used for the rejection of oil.

The combination of several or all of the foregoing possibilities withina synchronizing apparatus.

Consideration can be given to the partially necessary situation that inthe course of the above described friction surface combinations, theangle of the cone of the friction pairing and/or that of the frictionalsurfaces to one another can be modified.

BRIEF DESCRIPTIONS OF THE DRAWINGS

The invention will be described in more detail on the basis of thepreferred embodiments. In the drawings shown are:

FIG. 1 is an embodiment example of an outer synchronizer ring accordwith the invention with the recesses placed in the flange.

FIG. 2 is a longitudinal section through the synchronizer ring of FIG.1, along the line II, III-II, III.

FIG. 3 is a longitudinal section through the synchronizer ring of FIG.1, along the line II III-II, III showing an alternative embodiment tothat of the sectional view shown in FIG. 2.

FIG. 4 is a bottom view of an embodiment of an outer synchronizer ring,the flange of which is provided with a collar and recesses.

FIG. 5 is a longitudinal section through the synchronizer body in accordwith FIG. 4 along the line V—V.

FIG. 6 is a bottom view of an embodiment of an outer synchronizer ringwhich is provided with a flange and inwardly directed cams.

FIG. 7 is a longitudinal section through the synchronizer body of FIG.6, along the line VII—VII.

FIG. 8 is a view of an embodiment of a synchronizing apparatus withintegrated pressure elements and sliding sleeves.

FIG. 9 is a partial view synchronizing apparatus in accordance with FIG.8, in enlarged scale along the line IX—IX, showing an embodiment of anarrangement of synchronizer rings in accord with the drawing.

FIG. 10 is a further partial view of the synchronizing apparatus inaccordance with FIG. 8, in enlarged scale, along the line X—X with thesame embodiment as that in FIG. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1, an outer synchronizer ring designated by 1, is shown. Theouter synchronizer ring 1 is provided with a gear ring 2, a flange 3 andrecesses 4 located in the flange 3. As may be seen in FIG. 2, the bodyof the outer synchronizer ring 1 is fabricated in a conic shape. Afriction surface 23 is placed on its inner side wall. The gear ring 2 islocated on that end of the outer synchronizer ring 1 with the greaterconical diameter, and forms at the same time an end surface 1 b. Theflange 3, of the larger diameter of the cone, is aligned perpendicularlyto the longitudinal central axis 1 a of the outer synchronizer ring 1and extends radially outwardly. This flange 3 forms one end surface ofthe outer synchronizer ring 1. At the same time, the contact surface 3 cis formned, bounded by the inside diameters of said flange 3 b andflange 3 a, the latter having the smaller conical diameter. A stampedout detent 5 a, viewed in the axial direction, lies in alignment withand opposite to the recess 4. In FIG. 3, the same cross-section throughthe outer synchronizer ring 1 is presented, however, now on the endsurface 1 b, a punched through detent 5 b is provided as an alternativeto the presentation according to FIG. 2.

A further embodiment of an outer synchronizer ring 6 is shown in FIGS.4, 5. In this embodiment, a circumferential outer gear ring 7, a flange8 with a collar 9, and recesses 4 are provided. The collar 9 is bentparallel to the longitudinal axis 6 a of the outer synchronizer ring 6,with its free end pointing in the direction of the gear ring 7.

An embodiment of an outer synchronizer ring 10 in accord with theinvention with catches 11 is shown in FIG. 6. This outer synchronizerring 10 is constructed essentially like the outer synchronizer ring 1,but, in addition to its recesses 10 a, possesses inwardly projecting,radial catches 11. As can be seen from FIG. 7, the catches 11 project ina plane perpendicular to the longitudinal axis 10 b of the outersynchronizer ring 10 and extend themselves inward from the frictionsurface 24.

In FIGS. 8 to 10, an embodiment of an outer synchronizer ring 12 isshown, this being in particular, an embodiment of an arrangement of theinventive outer synchronizer rings. FIG. 8 shows a side view of asynchronizer body 13, upon which a slide sleeve 14 sits and into whichthe three pressure elements 15 are integrated. The synchronizer body 13possesses an inner tooth gear 13 a for a torque resistant arrangementwith a drive shaft (not shown). The synchronizer body 13 covers, in thisview an arrangement of synchronizer rings of the synchronizing apparatus12, which, however is depicted in FIGS. 9 and 10. Adjacent to thesynchronizer body 13 is placed a shift gear 16. The shift gear 16 isconnected to a clutch body 17, into the recesses 17 a in which catches18 a of an interposed ring 18 engage. The interposed ring 18 forms, withan outer synchronizer ring 19, a first friction pair 20 and with theinner synchronizer ring 21, a second friction pair 22. The inner flange21 a of the inner synchronizer ring 21, seen in this view, is partiallycovered by a shoulder 13 b of the synchronizer body 13. This innerflange 21 a is cut out by recesses. The shoulder 13 b engages in thesaid recesses and thus the inner synchronizer ring 21 is form-fit withthe synchronizer body 13. The pressure element 15 is moved by thesliding sleeve 14 during the pre-synchronizing against the contactingsurface 3 c of the flange 3 of the outer synchronizer ring 19.

The outer synchronizer ring 19 is form-fit connected with thesynchronizer body 13 by its flange 3. The form fit of the outersynchronizer ring 19 with the synchronizer body 13 is effected by meansof recesses 19 a in its flange 3. FIG. 10 shows this form-fitconnection. FIG. 10 shows a partial view of the same embodiment of asynchronizing apparatus as shown in FIG. 8 with the cross-sectionfollowing the section line X—X. The flange 3 of the outer synchronizerring 19 in this view is partially covered by an inner shoulder 13 c ofthe synchronizer body 13. This inner shoulder 13 c of the synchronizerbody 13 engages in the recess 19 a of the flange 3. Further, in thispresentation of FIG. 10, the inner flange 21 of the inner synchronizerring 21 is shown in an unobstructed manner.

Reference Numbers

1 Outer synchronizer ring

1 a Longitudinal axis

1 b End surface, larger flange

2 Gear ring

3 Flange

3 a I.D. of smaller flange

3 b O.D. of smaller flange

3 c Contact surface

4 Recesses

5 a Stamped detent in big flange

5 b Stamped through detent

6 Outer Synch. Ring

6 a Longitudinal axis

7 Ring gear

8 Flange, small diam.

9 Collar on 8

10 Outer Synch. Ring with catches

10 a Recesses

10 b Longitudinal center axis

11 Catch projections

12 Synchronizer apparatus

13 Synchronizer body

13 a Inner gearing (splines)

13 b Shoulder

13 c Inner shoulder

14 Sliding sleeve

15 Pressure element (ball)

16 Shift gear

17 Clutch body

17 a Recess

18 Interposed ring

18 a Engaging catch

19 Outer Synch. ring

19 a Recess

20 First friction pair

21 Inner Synch. ring

21 a Inner flange

22 Second friction pair

23 Friction surface

24 Friction surface

What is claimed is:
 1. A synchronizing apparatus (12) for a manual shifttransmission comprising: a stationary, synchronizer body (13) havingtorsional strength and circumferentially encompassing a gear shaft, amovable sleeve (14) on the synchronizer body (13), slidable along thelongitudinal axis of the gear shaft, at least one shift gear (16),rotatably placed on the gear shaft and which can be coupled to thesynchronizer body (13) by the moveable sleeve (14), which gear isprovided with a clutch body (17) or with a clutch gearing, and can bejoined to the synchronizer body (13) by the clutch body or the clutchgearing, at least one friction element connected to the shift gear (16),and at least one outer synchronizer ring (1, 6, 10, 19) having torsionalstrength connected to the synchronizer body, and wherein the outersynchronizer ring (1, 6, 10, 19) includes a conical annular body, with alarger diameter end thereof being proximal to the shift gear (16), and asmaller diameter end thereof being proximal to the synchronizer body(13), which is provided on an outer surface on a side with the greaterdiameter with a radially outwardly directed gear ring (2), an innersurface designed as a friction surface (23, 24) which coacts with afriction element, and the outer synchronizer ring (1, 6, 10, 19) is aone-piece sheet metal ring formed without chip removal, wherein theouter synchronizer ring (1, 6, 10, 19) includes on the end with thesmaller diameter a radially outwardly directed flange (3, 8) constructedin one piece with the outer synchronizer ring (1, 6, 10, 19).
 2. Asynchronizing apparatus in accordance with claim 1, wherein the flange(8) of the synchronizer ring (6) includes on a free end thereof a collar(9) turned up in the direction of the gear ring (2).
 3. A synchronizingapparatus in accordance with claim 1, wherein the torsional strength ofthe outer synchronizer ring (1, 6, 10, 19) is assured by at least onerecess (4, 10 a, 19 a) in the flange.
 4. A synchronizing apparatus inaccordance with claim 1, wherein the flange (3) of the outersynchronizer ring (1, 6, 10, 19) includes at least one recess (4, 10 a,19 a).
 5. A synchronizing apparatus in accordance with claim 4, whereinthe recess (4) of the outer synchronizer ring (1, 6, 10) coacts with atleast one detent (5 a, 5 b), which projects axially in a direction ofthe recess (4) and is installed in the gear ring (2), and the recess (4)lies directly opposite to and is aligned with the detent (5 a, 5 b). 6.A synchronizing apparatus in accordance with claim 1, wherein the outersynchronizer ring (10) is made with at least one radial catch (11) onthe smaller diameter end which projects inwardly from a rim of thefriction surface (24).
 7. A synchronizing apparatus in accordance withclaim 1, wherein the outer synchronizer ring (10) is provided with atleast one radially inwardly directed catch (11), projecting from a rimof the friction surface (24) at the smaller diameter end and the catch(11) is made from a metal flap which is stamped from the flange (3) anddisplaced to point radially inwardly.
 8. A synchrorizing apparatus inaccordance with the of claim 1, wherein the friction element comprisesan interposed ring.(18) with an outer friction surface taperinglyinclined toward a drive shaft as well as an inner friction surfacetaperingly inclined toward a drive shaft, the interposed ring (18) formsa first friction pairing (20) by an outer friction surface thereofcontacting with the friction surface (23) of the outer synchronizer ring(1, 6, 19), and by inner friction surface coacting with an innersynchronizer ring (21), the inner synchronizer ring (21) forms with theinner friction surface of the interposed ring (18), a second frictionpairing (22) by an additional outer friction surface taperingly inclinedtoward a drive shaft, and the inner synchronizer ring (21) connects withthe synchronizer body (13), the inner synchronizer ring (21) and theinterposed ring (18) are sheet metal parts formed without chip removal,and at least one recess (19 a) is cut out of the flange (3) therebyincreasing torsional strength.
 9. A synchronizing apparatus inaccordance with claim 8, wherein the inner synchronizer ring (21) isconnected to the synchronizer body (13) by at least one inwardlydirected radial, internal flange (21 a) extending from the frictionsurface (24) at the smaller diameter end.
 10. A synchronizing apparatusin accordance with claim 8, wherein for the manufacture of the outersynchronizer ring (1, 6, 10, 19) and the inner synchronizer ring (21) aswell as the interposed ring (18), sheet steel is employed and the firstfriction pair (20) and the second friction pair (22) are constructed ofsteel.
 11. A synchronizing apparatus in accordance with claim 8, whereinfor the manufacture of the outer synchronizer ring (1, 6, 10, 19) andthe inner synchronizer ring (21) as well as the interposed ring (18),sheet steel is employed and the first friction pair (20) and the secondfriction pair (22) are constructed of steel of different degrees ofhardness.
 12. A synchronizing apparatus in accordance with claim 8,wherein for the manufacture of the outer synchronizer ring (1, 6, 10,19) and the inner synchronizer ring (21) as well as the interposed ring(18), sheet steel is employed and the first friction pair (20) and thesecond friction pair (22) are constructed of steel having a differentsurface structure.
 13. A synchronizing apparatus in accordance withclaim 8, wherein for the manufacture of the outer synchronizer ring (1,6, 10, 19) and the inner synchronizer ring (21) as well as theinterposed rings (18) sheet steel is employed and the first frictionpair (20) and the second friction pair (22) are constructed of differentkinds of steel.
 14. A synchronizing apparatus in accordance with claim8, wherein for the manufacture of the outer synchronizer ring (1, 6, 10,19) and the inner synchronizer ring (21) as well as the interposed rings(18) sheet steel is employed and the first friction pair (20) and thesecond friction pair (22) are constructed of different kinds of steelhaving different degrees of hardness and different surface structure.